Production of unsaturated ketones



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PRODUCTION OF UNSATURATED KETGNEEi Richard Norman Lacey, Hull, England, assignor to The Distillers Company Limited, Edinburgh, Scotland, a

British company No Drawing. Filed Dec. 17, 1959, Ser. No. 860,081

Claims priority, application Great Britain Jan. 14, 1959 4 Claims. (til. 260-595) comprises contacting an allyl acetoacetate representable by the formula R2 I n -o-oooomoon with an aluminium compound representable by the forwherein R and R are alkyl groups or hydrogen atoms, R is a lower alkyl group, and at least one of the groups R and R is a lower alkyl group, the other group being a lower alkyl or a lower alkoxy group.

The allyl acetoacetate may be contacted with the aluminium compound with advantage at an elevated temperature, preferably at a temperature in the range from 100 to 300 C. The temperature used in any particular embodiment of the invention depends on the nature of the allyl acetoacetate heated; if, for instance, the allyl acetoacetate is methyl-butenyl acetoacetate, it may be heated at a temperature from 110 to 170 C., preferably from 140 to 170 C. The allyl acetoacetate is conveniently heated with the aluminium compound in an apparatus which enables a steady stream of carbon dioxide to be evolved and removed.

The aluminium compound used in the process of the invention may be, for example, aluminium tri-(acetylacetonate) or an aluminium tri-(alkyl acetoacetate) such as aluminium tri-(methyl acetoacetate) or aluminium tri- (ethyl acetoacetate). The tri-(acetylacetonate) may be prepared adding a solution of aqueous acetylacetone in ammonia to an aqueous solution of aluminium sulphate, neutralising the resulting mixture and removing the aluminium tri-(acetylacetonate) precipitated. The tri-(ethyl acetoacetate) and the tri-(methyl acetoacetate) may be prepared by reacting the ethyl acetoacetate or methyl acetoacetate with an aluminium tn'alkoxide, removing the alkanol produced and recovering the aluminium tri-(ethyl acetoacetate) or the aluminium tri-(methyl acetoacetate).

The following examples further illustrate the invention.

Examples 1 to 6 A series of samples of methylbutenyl acetoacetate were heated with an aluminium compound catalyst according to the present invention in a reactor fitted with a stirrer and a gas outlet, at various temperatures from 140 to 170 C., so that a steady stream of carbon dioxide was evolved from pyrolysis of the methylbutenyl acetoacetate,

v in! leaving methylhepteno-ne in the reactor. The nature and proportion of the aluminium compound, the temperature to which the mixture of methylbutenyl acetoacetate and the aluminium compound was heated and the yield of methylheptenone produced based on themethylbutenyl acetoacetate, are shown in the following table. The catalyst concentration is shown as millimoles of aluminium compound per mole of methylbutenyl acetoacetate. vIn the table is also included, as a comparison, the yield of methylheptenone obtained under the same conditions except that no aluminium compound catalyst was present.

Yield of Catalyst Temp., methyl- Example Catalyst concen- C. heptetration none,

' percent None 0 140-170 63. 5 1 Aluminium tit-(ethyl aceto acetate) 24 l40170 84 2 16 140-170 82. 8 8 Aluminium tri-(acetylacetonate) 24 140-170 83. 5 4. d0 16 163-165 83 do 16 140 82. 7 Aluminium tri-(methyl acetoacetate) 16 140-170 83 Example 7 Example 8 500 parts by weight of linalyl acetoacetate were heated with 10.9 parts by weight of aluminium tri-(acetylacetonate) as catalyst in a reactor maintained up to 210 C. The linalyl acetoacetate was pyrolysed to geranyl acetone.

The catalyst concentration was 16 millimoles per mole of linalyl acetoacetate.

The yield of geranyl acetone was 73%.

I claim:

1. A process of 'producing an unsaturated ketone representable by the formula which comprises contacting at a temperature in the range of to 300 C. an allyl acetoacetate representable by the formula with an aluminium compound representable by the foring of alkyl groups and hydrogen atoms, R is a lower Patented June 26, 1902 alkylgrou p, and R and R are selected from the group 4; A process claimed in claim 1 wherein the aluminium vconsisting of lower alkyl groups and lower alkoxy groups compound is aluminium tri-(ethyl acetoacetate).

at least one being a lower alkyl group.

2x A pmcess claimed in c1 aim 1 wherein ahmfinium References Cited in the file of this patent compound is aluminium tri-(acetylacetonate). v '7 5 UNITED STATES PATENTS 31 A process claimed in claim l wherein the aluminium 2,795,617 Kimel et a1. June 11, 1957 oompound is aluminium tri-(methyl acetoacetate). 2,839,579 Kimel et al. June 17, 1958 

1. A PROCESS OF PRODUCING AN UNSATURATED KETONE REPRESENTABLE BY THE FORMULA 